This is a resubmission of Mobile CHESS Research on Emergency Medical Services for Children by the University of Wisconsin's Center for Health Enhancement Systems Studies in collaboration with the University of Wisconsin Pediatric Asthma Clinical Research Program and five managed care organizations (MCO's) in Milwaukee County. This randomized control trial's primary aims are to test whether an interactive PDA supporting low income teenagers (ages 12-18) with significant asthma and MCO nurse case managers can improve: asthma control and reduce asthma-related emergency, urgent care visits, and hospitalizations. Secondary aims include testing whether this system increases adherence to asthma control medication and reduces school absenteeism. We will also examine a mediational model to help explain mechanisms by which this system has its effects. Four hundred Medicaid recipients (ages 12-18) with an asthma related urgent care or emergency visit in the last 12-months will be recruited into this study. All will receive their care (and be identified through electronic claims data) from the five participating MCO's serving Medicaid recipients in Milwaukee County. We anticipate a 20% dropout rate during the 12 month intervention. Subjects will be randomly assigned to one of two study arms and will participate in a 12-month intervention plus a 12-month follow-up period. All subjects will receive PDAs. Control group PDAs will offer limited asthma information, and collect and transmit posttest data. The experimental group's PDA will also: 1-access the internet, 2-deliver extensive text, audio and video asthma-related educational material, 3-deliver automated reminders and 4-allow communication with support groups and case manager.